1. Field of the Disclosure
The present invention relates generally to a roll assembly, and more particularly to a roll assembly that is able to move an object in multiple translative directions such as either of two generally perpendicular directions.
2. Description of the Related Art
One example use for a multi-translative roll assembly is in an imaging device such as a printer, copier, or automatic document feed scanner. In the imaging process used in such devices, a series of rolls and/or belts picks media from a media storage location and advances it in a media process direction along a media path through an image transfer or scanning section of the device. In order to precisely transfer an image to the media or precisely scan the media, it must be properly aligned in both the media process direction and a direction perpendicular to the media process direction. Otherwise, the printed or scanned image may be skewed or offset.
Alignment in the media process direction may be accomplished by controlling the timing of the advancement of the media through the image transfer or scanning section. Positioning the media perpendicular to the media process direction is typically accomplished using either an edge-referenced system or a center-referenced system, which commonly employs short edge-referenced portions to locate the media.
One conventional approach to edge reference media is to pass a side edge of the media through a rotating nip formed between a driven roll and a backup roll or “skew roll.” The driven roll has an axis perpendicular to the reference edge and the skew roll is angled slightly (e.g., four degrees) with respect to the driven roll to direct the media toward the reference edge. A relatively large amount of travel in the media process direction must be provided to allow sufficient space for the entire side edge of the media to migrate toward and meet the reference edge.
In order to increase the output speed of an imaging device, it is generally beneficial to shorten the length of the media path. However, a shorter media path provides less space to migrate the media toward the reference edge. Accordingly, it will be appreciated that a device that is able to selectively advance media in either a media process direction or toward a reference edge with little or no travel in the media process direction is desired to reduce the length of the media path. Such a device is also desired for applications outside the imaging industry where it is advantageous to be able to move objects in either of two generally perpendicular directions such as, for example, in a conveyor system on a manufacturing assembly line or a sorting line or on the wheels of a motorized vehicle such as, for example a forklift.